Description: Euphausiids constitute a major biomass component in shelf ecosystems and play a fundamental role in the rapid vertical transport of carbon from the ocean surface to the deeper layers during their daily vertical migration (DVM). DVM depth and migration patterns depend on oceanographic conditions with respect to temperature, light and oxygen availability at depth, factors that are highly dependent on season in most marine regions. Here we introduce a global krill respiration ANN (artificial neural network) model including the effect of latitude (LAT), the day of the year (DoY), and the number of daylight hours (DLh), in addition to the basal variables that determine ectothermal oxygen consumption (temperature, body mass and depth). The newly implemented parameters link space and time in terms of season and photoperiod to krill respiration. The ANN model showed a better fit (r2 = 0.780) when DLh and LAT were included, indicating a decrease in respiration with increasing LAT and decreasing DLh. We therefore propose DLh as a potential variable to consider when building physiological models for both hemispheres. For single Euphausiid species investigated in a large range of DLh and DoY, we also tested the standard respiration rate for seasonality with Multiple Linear Regression (MLR) and General Additive model (GAM). GAM successfully integrated DLh (r2 = 0.563) and DoY (r2 = 0.572) effects on respiration rates of the Antarctic krill, Euphausia superba, yielding the minimum metabolic activity in mid-June and the maximum at the end of December. We could not detect DLh or DoY effects in the North Pacific krill Euphausia pacifica, and our findings for the North Atlantic krill Meganyctiphanes norvegica remained inconclusive because of insufficient seasonal data coverage. We strongly encourage comparative respiration measurements of worldwide Euphausiid key species at different seasons to improve accuracy in ecosystem modeling.

Description: This progress report represents a follow up of WG-EMM-13/22 (WG-EMM, Jul 2013, Bremerhaven) and SC-CAMLR-XXXII/BG/07 (SC-CAMLR-XXXII, Oct 2013, Hobart). The authors intend to update the Working Group on Ecosystem Monitoring and Management on the actual state of our project, particularly on the proceeds of the data acquisition process and the preliminary scientific analysis. In addition, we present the report of the International Expert Workshop on the Weddell Sea MPA project (7-9 April 2014, Bremerhaven) as supplementary paper. The main objectives of this document are (i) to provide an updated summary of the data identification and acquisition process, (ii) to set out the preliminary scientific analysis which was worked out so far, (iii) to present on the report of the International Expert Workshop on the Weddell Sea MPA project (7-9 April 2014, Bremerhaven), and (iv) to give an update on the further process.

Description: Euphausiids constitute a major biomass component in shelf ecosystems and play a fundamental role in the rapid vertical transport of carbon from the ocean surface to the deeper layers during their daily vertical migration (DVM). DVM depth and migration patterns depend on oceanographic conditions with respect to temperature, light and oxygen availability at depth, factors that are highly dependent on season in most marine regions. Here we introduce a global krill respiration ANN (Artificial Neural Network) model including the effect of latitude (LAT), the day of the year (DoY), and the number of daylight hours (DLh), in addition to the basal variables that determine ectothermal oxygen consumption (temperature, body mass and depth). The newly implemented parameters link space and time in terms of season and photoperiod to krill respiration. The ANN model showed a better fit (r2=0.780) when DLh and LAT were included, indicating a decrease in respiration with increasing LAT and decreasing DLh. We therefore propose DLh as a potential variable to consider when building physiological models for both hemispheres. For single Euphausiid species investigated in a large range of DLh and DoY, we also tested the standard respiration rate for seasonality with Multiple Linear Regression (MLR) and General Additive model (GAM). GAM successfully integrated DLh (r2= 0.563) and DoY (r2= 0.572) effects on respiration rates of the Antarctic krill, Euphausia superba, yielding the minimum metabolic activity in mid-June and the maximum at the end of December. We could not detect DLh or DoY effects in the North Pacific krill Euphausia pacifica, and our findings for the North Atlantic krill Meganyctiphanes norvegica remained inconclusive because of insufficient seasonal data coverage. We strongly encourage comparative respiration measurements of worldwide Euphausiid key species at different seasons to improve accuracy in ecosystem modelling.

Description: In southern South America little is known about the biotic response of marine species to large scale climate variability during the Holocene. Fossil shells of the aragonitic bivalve Retrotapes exalbidus (previously called Eurhomalea) offer the possibility to investigate climate variability in the Beagle Channel and past seasonal dynamics of sea water temperature during the mid-to-late-Holocene. This selection is based on two reasons: extant R. exalbidus preserve annual increments in the outer shell layer (Lomovasky et al., 2002 J. Sea Research 48, 209-216); and, although not very common as other venerids, this species is well preserved in different Holocene marine outcrops along the channel. Holocene fossil shells of R. exalbidus were sectioned, polished, photographed and measured, and after examination three of them were selected for chemical sampling. In each case, one-half of the shell was used to resolve the annual growth bands and the other half was used for stable isotopes sampling. In addition, a fragment of each shell was used to C-14 dating performed in the Poznań Radiocarbon Laboratory with the accelerator mass spectrometry (AMS) technique. Ontogenetic ages were measured by counting the annual growth increments under a stereo microscope. Our results show differences between the three specimens. In the ontogenetic oldest individual (14 years), which gave a calibrated mean value age of 3839 BP, the δ18O values ranged from 1.53‰ to –1.16‰. The two other specimens (8 years), with calibrated mean ages of 5190 BP and 431 BP, gave δ18O values from 1.55‰ to 0.44‰ in the oldest specimen, and from 1.29‰ to 0.72‰, in the youngest one. Besides, we found variations in annual growth increment widths at different radiocarbon ages, probably correlated with environmental changes over the mid-to-late Holocene. We correlated the most positive δ18O values with winter and the most negative δ18O with summer. In addition, the summer values around 3800 yr BP are more negative than around 5000 years or 500 years BP. These findings correlate well with an episode of cooling at ca. 5000 BP, followed by a period of ameliorization (the Hypsithermal at ca. 4000 BP), and towards the end of the Holocene, at ca. 500 years BP, a new cooling event was recorded. This sclerochronological study of the growth patterns and the oxygen isotope ratios in fossil R. exalbidus shells demonstrated that this species clearly exhibited annual cycles showing seasonality patterns through the mid-to-late Holocene, providing an opportunity to analyze intra-seasonal time scales in the fossil record. This study was supported jointly by the CONICET and the DAAD and was made as part of the Scientific Visit of SG to the AWI and the international cooperation from MINCyT and BMBF to BL.

Description: The venerid Tawera gayi could be a suitable Holocene bioarchive for Southern South-America given that it is found in a wide distribution range from the Beagle Channel (54º 50´ S) to 33º S along the Pacific coast, and to the North Patagonia (36°S) in the South Atlantic. In the Beagle Channel, both extant T. gayi populations and shell beds of mid-Holocene origin can be found. On the other hand there is reliable life history information in modern populations (Lomovasky et al. 2005 J. Appl. Ichthyol. 21, 64-69), i.e. shell growth patterns and the confirmation of the annual periodicity of the translucent bands. Finally, the shells provide geochemical proxies, e.g., d18O for temperature reconstruction. In order to investigate climate variability in the Beagle Channel, the individual age, growth increments and isotopes analyses of modern and fossil shells of T. gayi were used. The shell cuts of T. gayi showed a pattern of alternating broad opaque and narrow translucent bands, which were confirmed by acetate peels too. In general, the translucent bands showed a pink to purple colour, similar to internal part of the shell. Both modern and fossil populations showed a maximum age of 13 years old. Radiocarbon dating revealed ages ranging between ca 3800 to 4400 years b.p. in the fossil shells corresponding to the Holocene Climate Optimum. The δ18O values obtained in fossil shells ranged from 1.316‰ to –0.064‰ We correlated the most positive δ18O values with winter forming the translucent bands and the most negative δ18O with summer. The comparison of the von Bertalanffy growth curve showed no difference in the H∞ between modern (32.50 mm; Confidence Interval (CI)=31.07, 33.94) and fossil (33.23 mm; CI=31.94, 34.51) populations, but higher values (p 〈 0.05) were observed in the growth rate k and t0 in the modern (0.37 (0.31, 0.42) and 1.12 (0.98, 1.25) respectively) than fossil shells (0.24 (0.21, 0.27) and 0.57 (0.44, 0.69) respectively). This study demonstrated that this species clearly exhibited annual cycles showing seasonality patterns from the mid-Holocene to the present with translucent bands corresponding to slow or halted growth formed in fall/winter; the growth rate was lower during the past warm epochs than the present possible related to a different productivity in the Channel and/or a lower metabolic rate of the clams exposed to a higher temperature.

Description: Amiantis purpurata is a typical warm-temperate water species distributed from southern Brazil to northern Patagonia, Argentina. Recent and well preserved fossil specimens were recovered from San Matías Gulf in northern Patagonia. Holocene (shell age 3630 ±100 years BP) and interglacial Pleistocene (MIS 5, 100 ka years BP) marine sediments were used for a comparative analysis of stable isotopic profiles (δ18O; δ13C). The values range of Pleistocene A. purpurata was from -0,93‰ to 0,85‰ for δ18O and from -1,02‰ to 1,9‰ for δ13C. Holocene shell was from -0,34‰ to 1,13‰ for δ18O and from 1,45‰ to 2,44‰ for δ13C. And Recent shell was from -0,66‰ to 1,56‰ for δ18O and from 0,7‰ to 2,6‰ for δ13C. The δ18O values indicate warmer waters in Pleistocene compared to Holocene and Recent. The intra-annual δ18O shell temperature is higher today (Δδ18ORecent=2,22‰) compared to the Holocene (Δδ18OHolocene=1,47‰) and the Pleistocene (Δδ18OPleistocene=1,76‰). Pleistocene δ13C range value was the widest (Δδ13CPleistocene=2,92‰), but Holocene (Δδ13CHolocene=0,98‰) and Recent (Δδ13CRecent=1,9‰) values were tighter and more positive than Pleistocene. This could be explained by changes in ocean circulation since San Matías Gulf would has been formed approaching 12 ka years BP (after MIS 5, Ponce et al. 2011 Biol. J. Linn. Soc. 103, 363–379). These shells showed a clear marine environment but with a difference in sea surface temperature and ocean circulation through geological time in northern Patagonia. Our findings indicate that A. purpurata is a suitable candidate for detailed paleoenvironment reconstructions in North Patagonia. Further analyses will show whether some notable events that occurred during the Holocene, such as the Neoglacial (early Holocene), the Hypsithermal (Middle Holocene) and the Little Ice Age (Late Holocene) have been recorded in fossil A. purpurata shells.

Description: Since the 1970s tremendous changes have been observed in the Arctic region. As such, the surface air temperature within this region has increased twice the global average and according to existing climate model predictions, this trend will continue in the future (IPCC, 2007). However, interpretation of such transformation, which results from greenhouse warming, is still difficult. This is due to a lack of knowledge about the influence of multi-annual to decadal climate variations and the fact that climatic data from this region are usually temporally and spatially biased. Therefore, a better understanding and further research on the effects and predictability of climate variability is needed. We examined the growth variability in shells of the bivalve Arctica islandica which is affected by environmental factors, mainly temperature or food supply. We compare shells from two sampling sites, the northern Norwegian coast and Kola Peninsula coast (SW Barents Sea). Both localities are in the realm of the Norwegian Coastal Current (after crossing the border to Russia it is called the Murman Coastal Current). For the investigation of the annual and inter-annual growth variability all collected shells were cut parallel to the line of strongest growth (LSG) and 3 mm thick-sections were attached to a glass slide. After grinding and polishing, the cross-sections were stained in Mutvei´s solution. Annual growth bands were identified and measured. Samples for the stable oxygen isotope (δ18O) analysis and the seasonality approach were taken using a hand drill and the milling technique. As our prime objective we compared the shell growth of the Norwegian and the Russian populations and determined the external factors controlling the annual shell growth variability in A. islandica. Furthermore, the shells from both populations have been checked for decadal oscillations (NAO? ACRI?). Finally, stable oxygen isotope ratio (δ18O) profiles have been measured to identify seasonal signals and to reconstruct regional water temperature variability at a sub-annual level.